This invention relates to a bulk shredder for shredding bulk material including plastic or wood material, construction and demolition waste, other fracturable or shreddable wood or plastic products, and especially railroad ties, utility poles and the like. The invention also relates to a method for shredding such material.
For shredding large objects such as railroad ties and demolition waste, it has been known to use heavy duty shredders which include a rotating auger within a shredding chamber. The material to be shredded is typically fed into one end of such a device and moved down the length of the shredding chamber by the auger towards a discharge end.
U.S. Pat. No. 5,108,040 discloses an auger shredder having a tapered auger which causes material to be shredded by the meshing of teeth on the auger periphery with breaker bars affixed to the shredding chamber. The auger is pinned at the input end of the shredder, where a drive motor for the auger is located, while the opposite end of the auger extends into an extrusion tube.
U.S. Pat. No. 4,976,471 discloses a mill for the comminution of plastic or wood into smaller pieces. The mill has a feeder screw which is driven by a motor with a discharge funnel adjacent the drive end.
U.S. Pat. Nos. 4,767,065, 5,011,088, and 4,632,317 also show auger-type material disintegrating devices having alternative designs.
U.S. Pat. No. 4,133,489 shows a shredding device having grate segments which are pivotably mounted at one end and moved at the other end by means of hydraulic jacks. U.S. Pat. No. 681,984 shows a pulverizer in which the lower screen is adjustable upward to accommodate for wear of the beater. U.S. Pat. Nos. 2,149,571, 3,829,030, and 4,009,836 show other pulverizers or hammer mills provided with adjustable grates or screens.
U.S. Pat. Nos. 4,042,183, 5,269,355, 5,148,999, and 4,978,078 show various configurations of various projections or teeth on augers for comminuting material.
Although certain of the prior designs such as that shown in U.S. Pat. No. 5,108,040 have proven to be adequate for shredding bulk material such as railroad ties, utility poles and the like, they suffer from certain inefficiencies. In particular, the auger teeth on certain such devices are not easily replaceable or are not configured for most efficiently shredding railroad ties and the like. The breaker bars on the shredder trough are not configured and oriented for most efficiently cooperating with the action of the auger teeth to shred such materials. Certain devices have a tapered auger or a drive means located at the end opposite the shredder's discharge end, which have been discovered to be undesirable for certain shredding operations. Also, they do not have the most effective bearing systems at both the drive end and opposite end of the auger shaft.